PURPOSE: To provide a container case for a magneto-optical disk cartridge or the like wherein the number of components is reduced to two, simplifying a structure, and a cost is reduced in a slide-in type cartridge container case

CONSTITUTION: A slide-in type case comprises two case pieces 12, 13 having a U-shaped cross section joining to each other on open ends to form a case. Openings 12b, 13b for receiving/removing a cartridge to be housed are provided on one end face with one of side plates perpendicular to the opening cut into a predetermined shape. In addition the case comprises a lever which can be elastically deformed inward and outward with respect to the case and has an engaging part to be fit into a slot 18 provided on a side end face of a housed cartridge 11 and a knob 15 which can be operated from outside.